ITHACA, N.Y. — Consider this T-shirt: It can monitor your heart rate and breathing, analyze your sweat and even cool you off on a hot summer’s day. What about a pillow that monitors your brain waves, or a solar-powered dress that can charge your ipod or MP4 player? This is not science fiction – this is cotton in 2010.

Now, the laboratory of Juan Hinestroza, assistant professor of Fiber Science and Apparel Design, has developed cotton threads that can conduct electric current as well as a metal wire can, yet remain light and comfortable enough to give a whole new meaning to multi-use garments. This technology works so well that simple knots in such specially treated thread can complete a circuit – and solar-powered dress with this technology literally woven into its fabric will be featured at the annual Cornell Design League Fashion Show on Saturday, March 13 at Cornell University’s Barton Hall.

Using multidisciplinary nanotechnology developed at Cornell in collaboration with the universities at Bologna and Cagliari, Italy, Hinestroza and his colleagues developed a technique to permanently coat cotton fibers with electrically conductive nanoparticles. “We can definitively have sections of a traditional cotton fabric becoming conductive, hence a great myriad of applications can be achieved,” Hinestroza said.

“The technology developed by us and our collaborators allows cotton to remain flexible, light and comfortable while being electronically conductive,” Hinestroza said. “Previous technologies have achieved conductivity but the resulting fiber becomes rigid and heavy. Our new techniques make our yarns friendly to further processing such as weaving, sewing and knitting.”

This technology is beyond the theory stage. Hinestroza’s student, Abbey Liebman, was inspired by the technology enough to design a dress that actually uses flexible solar cells to power small electronics from a USB charger located in the waist. The charger can power a smartphone or an MP3 player.

“Instead of conventional wires, we are using our conductive cotton to transmit the electricity — so our conductive yarns become part of the dress,” Hinestroza said. “Cotton used to be called the ‘fabric of our lives’ but based on these results, we can now call it ‘The fabric of our lights.'”

Led by Carl Batt, the Liberty Hyde Bailey Professor of Food Science, the researchers synthesized nanoparticles – shaped something like a dumbbell – made of gold sandwiched between two pieces of iron oxide. They then attached antibodies, which target a molecule found only in colorectal cancer cells, to the particles. Once bound, the nanoparticles are engulfed by the cancer cells.

To kill the cells, the researchers use a near-infrared laser, which is a wavelength that doesn’t harm normal tissue at the levels used, but the radiation is absorbed by the gold in the nanoparticles. This causes the cancer cells to heat up and die.

“This is a so-called ‘smart’ therapy,” Batt said. “To be a smart therapy, it should be targeted, and it should have some ability to be activated only when it’s there and then kills just the cancer cells.”

The goal, said lead author and biomedical graduate student Dickson Kirui, is to improve the technology and make it suitable for testing in a human clinical trial. The researchers are now working on a similar experiment targeting prostate cancer cells.

“If, down the line, you could clinically just target the cancer cells, you could then spare the health surrounding cells from being harmed – that is the critical thing,” Kirui said.

Gold has potential as a material key to fighting cancer in future smart therapies. It is biocompatible, inert and relatively easy to tweak chemically. By changing the size and shape of the gold particle, Kirui and colleagues can tune them to respond to different wavelengths of energy.

Once taken up by the researchers’ gold particles, the cancer cells are destroyed by heat – just a few degrees above normal body temperature – while the surrounding tissue is left unharmed. Such a low-power laser does not have any effect on surrounding cells because that particular wavelength does not heat up cells if they are not loaded up with nanoparticles, the researchers explained.

Using iron oxide – which is basically rust – as the other parts of the particles might one day allow scientists to also track the progress of cancer treatments using magnetic resonance imaging, Kirui said, by taking advantage of the particles’ magnetic properties.

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The research was funded by the Sloan Foundation and the Ludwig Institute for Cancer Research, which has been a partner with Cornell since 1999 to bring laboratory work to clinical testing. The research is reported in the Feb. 15 online edition of the journal Nanotechnology.

New adhesive device could let humans walk on walls

Could humans one day walk on walls, like Spider-Man? A palm-sized device invented at Cornell that uses water surface tension as an adhesive bond just might make it possible.

The rapid adhesion mechanism could lead to such applications as shoes or gloves that stick and unstick to walls, or Post-it-like notes that can bear loads, according to Paul Steen, professor of chemical and biomolecular engineering, who invented the device with Michael Vogel, a former postdoctoral associate.

The device is the result of inspiration drawn from a beetle native to Florida, which can adhere to a leaf with a force 100 times its own weight, yet also instantly unstick itself. Research behind the device is published online Feb. 1 in Proceedings of the National Academy of Sciences.

The device consists of a flat plate patterned with holes, each on the order of microns (one-millionth of a meter). A bottom plate holds a liquid reservoir, and in the middle is another porous layer. An electric field applied by a common 9-volt battery pumps water through the device and causes droplets to squeeze through the top layer. The surface tension of the exposed droplets makes the device grip another surface – much the way two wet glass slides stick together.

“In our everyday experience, these forces are relatively weak,” Steen said. “But if you make a lot of them and can control them, like the beetle does, you can get strong adhesion forces.”

For example, one of the researchers’ prototypes was made with about 1,000 300-micron-sized holes, and it can hold about 30 grams – more than 70 paper clips. They found that as they scaled down the holes and packed more of them onto the device, the adhesion got stronger. They estimate, then, that a one-square-inch device with millions of 1-micron-sized holes could hold more than 15 pounds.

To turn the adhesion off, the electric field is simply reversed, and the water is pulled back through the pores, breaking the tiny “bridges” created between the device and the other surface by the individual droplets.

The research builds on previously published work that demonstrated the efficacy of what’s called electro-osmotic pumping between surface tension-held interfaces, first by using just two larger water droplets.

One of the biggest challenges in making these devices work, Steen said, was keeping the droplets from coalescing, as water droplets tend to do when they get close together. To solve this, they designed their pump to resist water flow while it’s turned off.

Steen envisions future prototypes on a grander scale, once the pump mechanism is perfected, and the adhesive bond can be made even stronger. He also imagines covering the droplets with thin membranes – thin enough to be controlled by the pump but thick enough to eliminate wetting. The encapsulated liquid could exert simultaneous forces, like tiny punches.

“You can think about making a credit card-sized device that you can put in a rock fissure or a door, and break it open with very little voltage,” Steen said. “It’s a fun thing to think about.”

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The research was funded primarily by the Defense Advanced Research Projects Agency and also by the National Science Foundation.

Online poker study: The more hands you win, the more money you lose

ITHACA, N.Y. — A new Cornell study of online poker seems counterintuitive: The more hands players win, the less money they’re likely to collect – especially when it comes to novice players.

The likely reason, said Cornell sociology doctoral student Kyle Siler, whose study analyzed 27 million online poker hands, is that the multiple wins are likely for small stakes, and the more you play, the more likely you will eventually be walloped by occasional – but significant – losses.

This finding, Siler said, “coincides with observations in behavioral economics that people overweigh their frequent small gains vis-à-vis occasional large losses, and vice versa.” In other words, players feel positively reinforced by their streak of wins but have difficulty fully understanding how their occasional large losses offset their gains.

The study, which was published online in December in the Journal of Gambling Studies and will be published in a forthcoming print edition later this year, also found that for small-stakes players, small pairs (from twos to sevens) were actually more valuable than medium pairs (eights through jacks).

“This is because small pairs have a less ambiguous value, and medium pairs are better hands but have more ambiguous values that small-stakes players apparently have trouble understanding,” said Siler, a long-time poker player himself.

Siler used the software PokerTracker to upload and analyze small-stakes, medium-stakes and high-stakes hands of No-Limit Texas Hold’em with six seats at the table. The game has simple rules and “any single hand can involve players risking their entire stack of chips,” Siler said.

The research not only examined the “strategic demography” of poker at different levels of stakes and the various payoffs associated with different strategies at varying levels of play, but also “speaks to how humans handle risk and uncertainty,” said Siler, whose look at online poker combines aspects of behavioral economics, economic sociology and social science theory. “Riskiness may be profitable, especially in higher-stakes games, but it also increases the variance and uncertainty in payoffs. Living one’s life, calibrating multiple strategies and managing a bankroll is particularly challenging when enduring wild and erratic swings in short-term luck and results.”

In online poker, a multibillion dollar industry, Siler concluded that the biggest opponent for many players may be themselves, “given the challenges of optimizing one’s mindset and strategies, both in the card game and the meta-games of psychology, rationality and socio-economic arbitrage which hover beneath it,” he said.

Scanning electron micrograph of two thin, flat rings of silicon nitride, each 190 nanometers thick and mounted a millionth of a meter apart. Light is fed into the ring resonators from the straight waveguide at the right. Under the right conditions optical forces between the two rings are enough to bend the thin spokes and pull the rings toward one another, changing their resonances enough to act as an optical switch.Image from Cornell Nanophotonics Group

With a bit of leverage, Cornell researchers have used a very tiny beam of light with as little as 1 milliwatt of power to move a silicon structure up to 12 nanometers. That’s enough to completely switch the optical properties of the structure from opaque to transparent, they reported.

The technology could have applications in the design of micro-electromechanical systems (MEMS) — nanoscale devices with moving parts — and micro-optomechanical systems (MOMS) which combine moving parts with photonic circuits, said Michal Lipson, associate professor of electrical and computer engineering.

The research by postdoctoral researcher Gustavo Wiederhecker, Long Chen, Ph.D. ’09, Alexander Gondarenko, Ph.D. ’10, and Lipson appears in the online edition of the journal Nature and will appear in a forthcoming print edition.

Light can be thought of as a stream of particles that can exert a force on whatever they strike. The sun doesn’t knock you off your feet because the force is very small, but at the nanoscale it can be significant. “The challenge is that large optical forces are required to change the geometry of photonic structures,” Lipson explained.

But the researchers were able to reduce the force required by creating two ring resonators — circular waveguides whose circumference is matched to a multiple of the wavelength of the light used — and exploiting the coupling between beams of light traveling through the two rings.

A beam of light consists of oscillating electric and magnetic fields, and these fields can pull in nearby objects, a microscopic equivalent of the way static electricity on clothes attracts lint. This phenomenon is exploited in “optical tweezers” used by physicists to trap tiny objects. The forces tend to pull anything at the edge of the beam toward the center.

When light travels through a waveguide whose cross-section is smaller than its wavelength some of the light spills over, and with it the attractive force. So parallel waveguides close together, each carrying a light beam, are drawn even closer, rather like two streams of rainwater on a windowpane that touch and are pulled together by surface tension.

The researchers created a structure consisting of two thin, flat silicon nitride rings about 30 microns (millionths of a meter) in diameter mounted one above the other and connected to a pedestal by thin spokes. Think of two bicycle wheels on a vertical shaft, but each with only four thin, flexible spokes. The ring waveguides are three microns wide and 190 nanometers (nm — billionths of a meter) thick, and the rings are spaced 1 micron apart.

When light at a resonant frequency of the rings, in this case infrared light at 1533.5 nm, is fed into the rings, the force between the rings is enough to deform the rings by up to 12 nm, which the researchers showed was enough to change other resonances and switch other light beams traveling through the rings on and off. When light in both rings is in phase — the peaks and valleys of the wave match — the two rings are pulled together. When it is out of phase they are repelled. The latter phenomenon might be useful in MEMS, where an ongoing problem is that silicon parts tend to stick together, Lipson said.

An application in photonic circuits might be to create a tunable filter to pass one particular optical wavelength, Wiederhecker suggested.

The work is supported by the National Science Foundation (NSF) and the Cornell Center for Nanoscale Systems. Devices were fabricated at the Cornell Nanoscale Science and Technology Facility, also supported by NSF.

New nanolaser key to future optical computers and technologies

Because the new device, called a “spaser,” is the first of its kind to emit visible light, it represents a critical component for possible future technologies based on “nanophotonic” circuitry, said Vladimir Shalaev, the Robert and Anne Burnett Professor of Electrical and Computer Engineering at Purdue University.

Such circuits will require a laser-light source, but current lasers can’t be made small enough to integrate them into electronic chips. Now researchers have overcome this obstacle, harnessing clouds of electrons called “surface plasmons,” instead of the photons that make up light, to create the tiny spasers.

Findings are detailed in a paper appearing online Sunday (Aug. 16) in the journal Nature, reporting on work conducted by researchers at Purdue, Norfolk State University and Cornell University.

Nanophotonics may usher in a host of radical advances, including powerful “hyperlenses” resulting in sensors and microscopes 10 times more powerful than today’s and able to see objects as small as DNA; computers and consumer electronics that use light instead of electronic signals to process information; and more efficient solar collectors.

“Here, we have demonstrated the feasibility of the most critical component – the nanolaser – essential for nanophotonics to become a practical technology,” Shalaev said.

The “spaser-based nanolasers” created in the research were spheres 44 nanometers, or billionths of a meter, in diameter – more than 1 million could fit inside a red blood cell. The spheres were fabricated at Cornell, with Norfolk State and Purdue performing the optical characterization needed to determine whether the devices behave as lasers.

The findings confirm work by physicists David Bergman at Tel Aviv University and Mark Stockman at Georgia State University, who first proposed the spaser concept in 2003.

“This work represents an important milestone that may prove to be the start of a revolution in nanophotonics, with applications in imaging and sensing at a scale that is much smaller than the wavelength of visible light,” said Timothy D. Sands, the Mary Jo and Robert L. Kirk Director of the Birck Nanotechnology Center in Purdue’s Discovery Park.

The spasers contain a gold core surrounded by a glasslike shell filled with green dye. When a light was shined on the spheres, plasmons generated by the gold core were amplified by the dye. The plasmons were then converted to photons of visible light, which was emitted as a laser.

Spaser stands for surface plasmon amplification by stimulated emission of radiation. To act like lasers, they require a “feedback system” that causes the surface plasmons to oscillate back and forth so that they gain power and can be emitted as light. Conventional lasers are limited in how small they can be made because this feedback component for photons, called an optical resonator, must be at least half the size of the wavelength of laser light.

The researchers, however, have overcome this hurdle by using not photons but surface plasmons, which enabled them to create a resonator 44 nanometers in diameter, or less than one-tenth the size of the 530-nanometer wavelength emitted by the spaser.

“It’s fitting that we have realized a breakthrough in laser technology as we are getting ready to celebrate the 50th anniversary of the invention of the laser,” Shalaev said.

Future work may involve creating a spaser-based nanolaser that uses an electrical source instead of a light source, which would make them more practical for computer and electronics applications.

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The work was funded by the National Science Foundation and U.S. Army Research Office and is affiliated with the Birck Nanotechnology Center, the Center for Materials Research at Norfolk State, and Cornell’s Materials Science and Engineering Department.

IMAGE CAPTION:

Researchers have created the tiniest laser since its invention nearly 50 years ago. Because the new device, called a “spaser,” is the first of its kind to emit visible light, it represents a critical component for possible future technologies based on “nanophotonic” circuitry. The color diagram (a) shows the nanolaser’s design: a gold core surrounded by a glasslike shell filled with green dye. Scanning electron microscope images (b and c) show that the gold core and the thickness of the silica shell were about 14 nanometers and 15 nanometers, respectively. A simulation of the SPASER (d) shows the device emitting visible light with a wavelength of 525 nanometers. (Birck Nanotechnology Center, Purdue University)

One explanation given for opposition to same-sex marriage is the so-called “ick” factor. That is revulsion against the very idea of homosexuality by heterosexuals.

Take this for what it’s worth because it smells a lot like a solution in search of problem, but here’s research from Cornell connecting that very response with a group largely against same-sex marriage — political conservatives.

Food for thought if nothing else.

The release (yeah, I know I said the release dump was over with the last post):

Are you someone who squirms when confronted with slime, shudders at stickiness or gets grossed out by gore? Do crawly insects make you cringe or dead bodies make you blanch?

If so, chances are you’re more conservative — politically, and especially in your attitudes toward gays and lesbians — than your less-squeamish counterparts, according to two Cornell studies.

The results, said study leader David Pizarro, Cornell assistant professor of psychology, raise questions about the role of disgust — an emotion that likely evolved in humans to keep them safe from potentially hazardous or disease-carrying environments — in contemporary judgments of morality and purity.

In the first study, published in the journal Cognition & Emotion (Vol.23: No.4), Pizarro and co-authors Yoel Inbar of Harvard University’s Kennedy School of Government and Paul Bloom of Yale University surveyed 181 U.S. adults from politically mixed “swing states.” They subjected these adults to two indexes: the Disgust Sensitivity Scale (DSS), which offers various scenarios to assess disgust sensitivity, and a political ideology scale. From this they found a correlation between being more easily disgusted and political conservatism.

To test whether disgust sensitivity is linked to specific conservative attitudes, the researchers then surveyed 91 Cornell undergraduates with the DSS, as well as with questions about their positions on issues including gay marriage, abortion, gun control, labor unions, tax cuts and affirmative action.

Participants who rated higher in disgust sensitivity were more likely to oppose gay marriage and abortion, issues that are related to notions of morality or purity. The researchers also found a weak correlation between disgust sensitivity and support for tax cuts, but no link between disgust sensitivity and the other issues.

And in a separate study in the current issue of the journal Emotion (Vol.9: No.3), Pizarro and colleagues found a link between higher disgust sensitivity and disapproval of gays and lesbians. For this study, the researchers used implicit measures (measures that have been shown to assess attitudes people may be unwilling to report explicitly; or that they may not even know they possess).

Liberals and conservatives disagree about whether disgust has a valid place in making moral judgments, Pizarro noted. Conservatives have argued that there is inherent wisdom in repugnance; that feeling disgusted about something — gay sex between consenting adults, for example — is cause enough to judge it wrong or immoral, even lacking a concrete reason. Liberals tend to disagree, and are more likely to base judgments on whether an action or a thing causes actual harm.

Studying the link between disgust and moral judgment could help explain the strong differences in people’s moral opinions, Pizarro said; and it could offer strategies for persuading some to change their views.

“People have pointed out for a long time that a lot of our moral values seem driven by emotion, and in particular, disgust appears to be one of those emotions that seems to be recruited for moral judgments,” said Pizarro.

That can have tragic effects — as in cases throughout history where minorities have been victims of discrimination by groups that perceived them as having disgusting characteristics.

The research speaks to a need for caution when forming moral judgments, Pizarro added. “Disgust really is about protecting yourself from disease; it didn’t really evolve for the purpose of human morality,” he said. “It clearly has become central to morality, but because of its origins in contamination and avoidance, we should be wary about its influences.”

The research will allow for creating a “lab on a chip,” in which a tiny biological sample would be carried through microscopic channels for processing. This could make possible portable, fast-acting detectors for diseaseorganisms or food-borne pathogens, rapid DNA sequencing and other tests that now take hours or days.

The apparatus uses a “slot waveguide” — two parallel silicon bars 60 nm apart, serving as two parallel wave guides. Light waves traveling along each guide expand beyond its boundaries, but because the parallel guides are so close together, the waves overlap and most of the energy is concentrated in the slot. In addition to creating a more intense beam, this structure allows a beam of light to be channeled through air or water.

Replacing bulk with nanotechnology, researchers find new way to keep fiber-optic signal sharp

Nanowerk News, Feb. 20, 2008

Cornell researchers have demonstrated that a single photonic microchip–using four-wave mixing to amplify an optical signal by “pumping” with another beam of light–can replace the bulky bundles of fiber or electronic amplifiers now needed to clean up and sharpen fiber optic signals distorted by distance.